In hydraulic and pneumatic cylinders and similar assemblies, it is generally necessary to provide means for sealably engaging a rotating and/or reciprocating shaft, piston, ram or similar member to prevent the ingress of soil, moisture or other contaminates or the egress of oil, air, grease or other actuating or lubricating substances.
Such sealing engagement normally is accomplished through use of a resilient ring type seal seated in a closely fitting groove which is machined or otherwise formed in the bore of an elongate cylinder, sleeve, or the like. As the seal is seated in this groove, its outside periphery obviously must be larger than the circumference of the bore in which the groove is formed. Thus, if a seal should be molded or otherwise made of a relatively stiff material, such as Teflon, Nylon, urethane or polyproplene, considerable difficulty may be experienced in deforming it sufficiently to permit its convenient introduction into and movement through the bore, while simultaneously holding it in such position that it will properly enter and seat in the groove. And particularly if the bore is of relatively small diameter or the seal is unusually stiff and/or the groove is spaced a substantial distance within the bore, such emplacement can become quite time consuming and troublesome.
Over the years, various suggestions have been advanced for processes and/or devices intended to reduce or alleviate the problems associated with the emplacement of such seals. As examples of such prior proposals, attention is called to the following representative U.S. Pat. Nos. 3,180,015; 3,990,138; 3,406,441; 4,027,372; 3,455,011.
As far as is known, however, such prior processes and/or devices have been quite limited in their usefulness, and have met with little or no significant commercial success. For instance, U.S. Pat. Nos. 3,180,015--3,406,441 and 4,027,372 show structures containing axially slidable members which not only require that a seal be stretched longitudinally but simultaneously bent at substantially a right angle preparatory to its entry into a bore and placement in the groove. Thus, the practical usefulness of such devices is limited almost exclusively to highly flexible seals (i.e. the usual O-ring) which can readily accommodate simultaneous and relatively severe distortion and bending.
The device taught in U.S. Pat. No. 3,990,138 not only involves a relatively complex structure, but would appear to present problems in terms of the assembly of the seal with the tool preparatory to emplacement of the seal. For example, unless it should be quite flexible and of a definite predetermined size, the average user could experience difficulty in "threading" the seal manually around the transversely fixed pins provided by the embodiment of FIGS. 4-7 of this prior patent.
The pliers type tool of U.S. Pat. No. 3,455,011 represents a somewhat simpler and more practical approach, in that the seal is easily disposed on the jaws of this device, and the jaws are operated by a simple squeezing action. Even in this instance, however, problems would be encountered in stretching a seal sufficiently around the back curved portion of the horseshoe shaped jaw to permit its proper deflection into the front slot--particularly if the user should lack a strong grip or if the seal should be relatively stiff and/or of sufficient thickness to wedge between the movable "pin" jaw and the mouth of the slot. Further, because of the fixed size of the horseshoe shaped jaw, this prior device would be quite limited in terms of its potential usefulness with cylinders and sleeves of various diameters.
Accordingly, while various suggestions have been proposed in an effort to solve the long recognized problems normally encountered in attempting to emplace various types of seals, such prior proposals have failed to provide an inexpensive, relatively simple, rugged, easily handled device which is adapted for use with seals of various degrees of resiliency and of various sizes and configurations, and with cylinders of various diameters and lengths.